Solid freeform fabrication (SFF) or layer manufacturing (LM) is a fabrication technology that builds an object of any complex shape layer by layer or point by point without using a pre-shaped tool (die or mold). This process begins with creating a Computer Aided Design (CAD) file to represent the geometry of a desired object. SFF technology enables direct translation of the CAD image data into a three-dimensional object. SFF technology can be used in applications such as verifying CAD database, evaluating design feasibility, testing part functionality, assessing aesthetics, checking ergonomics of design, aiding in tool and fixture design, creating conceptual models and sales/marketing tools, generating patterns for investment casting, reducing or eliminating engineering changes in production, and providing small production runs.
One SFF technique involves adding or depositing a build composition to form predetermined areas of a layer essentially point-by-point. These predetermined areas together constitute a thin section of a three-dimensional object as defined by a CAD geometry. Successive layers are then deposited in a predetermined sequence with a layer being affixed to its adjacent layers forming an integral three dimensional, multi-layer object.
In a powder/binder SFF system an individual layer is printed by first spreading a thin layer of the powder and then dispensing the binder to adhere the powder together in selected regions to create the desired layer pattern. This process is repeated until all the layers have been printed. The binder joins powder together within a layer and between layers. After printing is complete, the unbound powder is removed, leaving a three-dimensional object with the desired geometry.